Foundry compositions containing propylene glycol monoacetate

Abstract

The present invention relates to foundry compositions containing propylene glycol monoacetate, a silica base and a silicate. The use of propylene glycol monoacetate as ester hardeners imparts greater compressive strength to foundry cors and the strength is built up more rapidly than with conventional ester hardeners. This is believed to be due at least in part to the total miscibility of this ester with water and to the purity of the ester product.

I claim: 
     
       1. A foundry composition comprising a silica base, a silicate and propylene glycol monoacetate. 
     
     
       2. A composition according to claim 1 wherein the silica base is sand. 
     
     
       3. A composition according to claims 1 wherein the silicate is an alkali metal silicate or an alkaline earth metal silicate. 
     
     
       4. A composition according to claim 3 wherein the silicate is sodium silicate. 
     
     
       5. A composition according to claim 4 wherein the silicate has a high silica to sodium oxide molecular ratio. 
     
     
       6. A silicate according to claim 5 wherein the silicate has a silica to sodium oxide molecular ratio between 2:1 and 3:1. 
     
     
       7. A composition according to claim 6 wherein the silicate has a silica to sodium oxide molecular ratio of between 2.5:1 and 2.8:1. 
     
     
       8. A composition according to claim 1 wherein propylene glycol monoacetate is used as a mixture thereof with a hardener selected from diacetin, triacetin, ethylene glycol diacetate and diethylene glycol diacetate. 
     
     
       9. A composition according to claim 8 wherein the mixture contains at least 50% by weight of propylene glycol monoacetate. 
     
     
       10. A composition according to claim 1 wherein the amount of propylene glycol monoacetate added to the silicate is between 1 and 20% by weight of the silicate.